With an increase in the capacity of a magnetic disk device, the capacity of a recent Redundant Arrays of Inexpensive Disks (RAID) device has increased. In order to ensure the quality of the magnetic disk device, the RAID device includes a disk patrol function of scanning the whole region of the magnetic disk device in accordance with a verify command in a process other than a normal I/O process.
Japanese Laid-open Patent Publication No. 2008-217141 is an example of the related art.
The conventional disk patrol function causes the RAID device to issue the verify command to the magnetic disk device of a RAID group at time intervals of 2 seconds in the process other than the normal I/O process and scans the whole region of the magnetic disk device.
In this case, when the capacity of the magnetic disk device is 1 TB, the scan needs to be performed for approximately 9 months. In addition, when the verify command is issued at time intervals of 2 seconds or less, the scan may be performed at a higher speed. However, the normal I/O process is adversely affected.